The drive unit for lifting systems usually comprises wires, tooth belts or chains.
Chain drives become acoustically or physically noticeable when the chain is caused to vibrate. The most common cause for such vibrations is the so called polygon effect that occurs, when the drive wheel engages with the chain in a form-fit. Since the chain cannot continuously roll-on or -off the drive wheel, angular offsets of the chain occur, so that the drive wheel forms a polygon. As a result, vibrations in the longitudinal and the transversal direction of the chain occur.
Usually, to prevent these vibrations, chains with a small pitch, chain wheels with an increased number of teeth or other means like wires, tooth chains or tooth belts are being used. In comparison to roller chains, tooth chains are very expensive and tooth belts have a limited life time.